It brings to mind the commonality of racism and xenophobia. At the moment I'm thinking of the era of serious carnage that went on between the city-states of ancient Greece, as if an Athenian was as reviled by a Spartan (or vice versa) as, say, the blacks during the American "Jim Crow" era.
There are plenty of hostilities between people of the same color and even common ancestry to remind us that people hate people for all kinds of stupid and petty reasons, but the consequences often go as far as the worst of human rights violations ever known to happen. I think it was Elie Wiesel who said (of the Holocaust) that the Germans had pushed the limits of human cruelty so far than ever conceivable that the lexicon did not contain the words to describe it; that "they forced us to invent words" like the Holocaust to name the newly created crimes. (I'm sure I mangled his quote.)
Racists are sick puppies. (Here I'm just addressing the topic in general.) It takes a mean person to intentionally harm another person. But to do so for stupid and petty reasons and with a degree of hatred that can foment violence and the serious infringement of a person's rights is psychopathic.
This thread may be kind of off in the weeds anyway, but anyone who would seriously ask about how to cure a person of racism is asking the wrong question. It needs to begin with the observation that it's a serious behavioral and thinking disorder which may not be treatable, and is more often merely punishable. Fortunately there are an abundance of laws to refer to that impose penalties for violating other folks' civil rights.
It's kind of an anachronism anyway. More relevant might be to ask why people hate immigrants, or people who eat different kinds of food, or dress or look different, or speak unintelligibly in foreign tongues or with certain kinds of accents. I find this kind of thinking and behavior appalling. It comes to mind every time the immigration issue comes up in the American right wing political diatribes.
Recently Republican governor Jan Brewer of Arizona, in opposition to President Obama's executive order granting amnesty to immigrant children who were advancing their education (the "Dream Act")--the order circumvented Congress where Republican hate-mongering had it bogged down--Gov Brewer came up with her own order to deny state driver's licenses to young people who may apply for amnesty under the Dream Act.
Gov Brewer is a psychopath. Any person who would wield power to harm another person on account of mean and stupid urges arising out of something as petty as xenophobia ought to be committed to the state prison until a cure, if any, is reached. She is dangerous and should not be allowed in public, much, much less than to wield power over her victims. She compounds her crime by taking political gain from it, pandering to the xenophobes in her electorate.
At this point I would rhetorically ask the thread starter to go work magic on Gov Brewer. It can't be done. I would however, favor a period of incarceration--in a bull pen full of bull dyke Latino women--while undergoing intensive therapy. Shock therapy, if necessary, while on a diet of 100% Mexican food, with Mexican conjunto music blaring 24/7, and only Spanish spoken and written within her place of confinement.
That might serve as a cure.
So called racism starts by disliking one person then if you have a second experience with such ethnic personality you start generalize your thinking if you experience a group as you mention in your last paragraph then you type group will consider you as a racist. But you can change you attitude by marring a good Spanish girl and enjoy the conjunto music 24/7